gunrunnerjohn posted:… I'll be dipped if I can find any more information about the mystery USB cable
My guess is the cable is a more than a connector and wires...maybe something like this FTDI converter for 3V RS-232 to USB. There's a microcontroller chip inside the molded USB connector and wire-ends on the voltmeter side as suggested in their photo.
The "cable" costs as much as the voltmeter itself!